4.137 - [expand] Built-In

Convert whitespace-separated strings, stripped of any leading and/or trailing non-alpha characters, by extracted lowercase alpha keywords against the supplied dictionary.

Whitespace is collapsed by this built in.

If a keyword has its first letter capitalized, then the first letter of the expansion will also be capitalized. The keyword is determined as follows:

Leading and trailing non-alpha characters are not used as part of the keyword but will remain present around any expansion; non-alpha characters between the first and last alpha characters, whether inside leading and trailing non-alpha characters or not, are not part of the keyword.

The expansion can be more than one word and may contain any character simply based on what is in the dictionary entry.

Keywords are converted to lower case before they are used to determine which dictionary entry to use, so only lower-case keys will enable expansion.